One man’s trash is another man’s treasure, or so the saying goes. Waste-to-Energy technology takes many people’s trash and makes it into usable energy, at the same time reducing landfill carbon footprints. As the United States pursues carbon legislation and alternative energy sources, what role will trash have?
Waste-to-Energy is a technology that burns municipal solid waste to generate electricity and can provide heat for buildings or industrial processes. Instead of dumping garbage into a landfill, the waste is taken to a WTE plant where it is used as fuel for making steam and generating electricity. This process reduces the final volume of the trash it burns by 90 percent and simultaneously reduces the carbon footprint of the landfill by converting methane to carbon dioxide. These advantages have made WTE technology attractive to many cities, including Austin.
The City of Austin already has a history with Waste-to-Energy that dates back 30 years. In the early 1980s, city staff and outside consultants projected that a WTE plant would have lower tipping fees than a landfill. In 1984, Austin voters approved a bond to build a $71 million WTE facility in southeast Austin. A design firm was hired, a site selected, and $20 million worth of design and purchasing of equipment was performed. In the meantime, environmental and environmental justice groups protested the city’s decision, energy prices dropped, and the project budget grew to more than $80 million, making the project less attractive. In 1988, City Council bowed to public pressure and cancelled the project. In 1991 the last of the lawsuits related to the plant was settled, and in 1992 Austin voters approved a ballot measure deauthorizing the WTE project.
As the United States pursues carbon legislation and alternative energy sources, converting trash to usable energy may provide another viable technology option. In deciding what role WTE should have in the future energy economy, we should understand the pros and cons of this technology.
While our waste is normally regarded as an unsightly byproduct of our everyday lives, there are many benefits to using it as a fuel. In addition to generating electricity, WTE plants reduce the volume of waste by 90 percent, meaning less space is needed for landfills. WTE is also considered partially “carbon-neutral” (i.e. it does not contribute to global climate change) because approximately two-thirds of the carbon in our waste is from recent biological sources: food waste, paper, wood, grass clippings, etc. Finally, the ash that is sent to the landfill is inert, so it does not decompose to form landfill gas, which is composed primarily of carbon dioxide and methane, a greenhouse gas with approximately 25 times the warming effect of carbon dioxide.
Not everything is pristine with the WTE process. Despite some greenhouse gas advantages, WTE has a reputation for emitting high levels of pollution. Municipal solid waste contains a wide variety of items that are burned and then potentially emitted into the air. Historically, WTE plants emitted high levels of mercury, lead, particulates, SOx and NOx and dioxins. However, today’s WTE plants are regulated by the Clean Air Act and therefore have much lower emissions of these pollutants — in some cases, lower than a coal plant, on a per-kWh of electricity produced basis. There are still many people who are concerned about the air emissions from these WTE plants, but recent studies of emissions from modern plants and the landfills where the ashes are buried have shown that there is minimal risk from the emissions.
…And the Ugly
WTE plants are expensive. In fact, the cost appears to have increased substantially since the 1980s. WTE plants only make economic sense in areas that don’t have the space to create new landfills. There are hundreds of WTE plants across the world, but these are mostly concentrated in densely populated areas – places like Europe, Japan and the East Coast. In these areas, WTE facilities are economically competitive because landfill space is at a premium. Tipping fees, charged to customers to dispose of municipal solid waste, are well above $50 per ton in these areas, compared to about $20 per ton here in central Texas.
One issue that might change the economic equation is carbon legislation. Landfills are required to install methane collection systems, but they do not capture all of the methane created. Any methane that escapes goes into the atmosphere and contributes to global climate change. If carbon legislation is enacted, it is possible that WTE plants could claim credits for eliminating the fugitive methane emissions, or landfills could face increased costs for more elaborate systems to capture more of the landfill gases. If the economics of waste disposal change enough, we could see the WTE industry expand into areas where it has historically not made economic sense.
Waste-to-energy technology takes waste and makes it into a valuable commodity – energy. But, there are also downsides to this technology including air emissions, public aversion and unfavorable economics for areas (like Austin) with low tipping fees. Ultimately, the price associated with greenhouse gases will determine the future of WTE in the United States. We’ll have to see what legislation is advanced to evaluate the potential impact on this industry.